A Fast and Direct Amperometric Determination of Hg2+ by a Bienzyme Electrode Based on the Competitive Activities of Glucose Oxidase and Laccase

A new concept of enzyme inhibition-based biosensor involving the appearance of an amperometric signal for an inhibition by mercury was developed. The bienzyme sensor was composed of two layers of clay materials. The inner layer was constituted of layered double hydroxides entrapping laccase wired by ABTS. The outer laponite layer contained glucose oxidase (GOD). GOD catalyzed the glucose oxidation with the reduction of O-2 into H2O2. This induced a drastic decrease of the biosensor response to O-2 by the electrically wired laccase. HgCl2 inhibited the O-2 consumption by GOD leading to a signal increase of the electroenzymatic reduction of O-2.